To make the sauce: In a small bowl, whisk together the mayonnaise, ketchup, relish and vinegar. Season to taste with salt and pepper.

To make the burgers: Divide the ground beef in half and form into patties, making sure not to overwork the meat. Liberally season both sides and the edges with salt and pepper.

Heat a large cast iron skillet over medium-high heat. Add the oil and the seasoned burgers. Use your spatula to firmly smash the burger into the skillet. Cook on one side until a crust has formed on the bottom, about 5 minutes. Evenly spread the mustard on the raw side, then flip the burgers so that the mustard is now on the bottom. Smash the burger again, and the cook another 5 minutes (for medium). Place one slice of cheese on each burger to melt. Transfer the burgers to a plate and let rest for 5 minutes.

To assemble, evenly spread the secret sauce on both interior sides of the buns. Place the lettuce on the bottom bun, followed by the pickles, then the burger patty. Serve.

Photo Credit: Ideabar Austin

About the recipe

Cooking burgers (or any meat for that matter) in a cast iron skillet gives the meat a wonderful caramelized crust. We're upping that burger crust even more by giving each patty a good smash with our spatula as they cook in the skillet. Another trick? We're adding mustard directly into the patty, letting the savory condiment cook its way into the crust of the meat itself.

Try to find beef that is 75 or 80 percent lean. Anything leaner will make for a dry burger with a grainy texture.

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